ABSTRACT
In present paper authors examine the conditions for which the fault motion exhibits stick-slip like dynamics, under the main assumption that a fault filling at least along a certain part of the fault possesses viscous properties. Analysis is conducted for the mechanical spring-block model of fault motion, suggesting that two neighboring parts of a fault, whose friction could be described by Dieterich-Ruina law, are separated by a viscous part of a fault filling, due to increased temperature, fluidization and melting. This initial assumption follows the original suggestion of Burridge and Knopoff, but with the introduced time delay in transition of the motion between the two blocks. Analysis is conducted using local bifurcation analysis, and by numerically solving the observed system of delay differential equations using Runge-Kutta 4th order method. Starting system, without the introduced time delay, exhibits only the first direct and inverse supercritical Andronov-Hopf bifurcation. Results obtained indicate that the effect of nonstationary time delay force the system under study to exhibit stick-slip like dynamics, which corresponds qualitatively well to full seismic cycle, with alternation of inter-seismic and co-seismic fault motion. Results obtained emphasize the role of viscous regions along the fault on seismogenic dynamics.
